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Build a “Brand Twin” That Writes Every Post in Your Exact Voice

Learn how to create a custom GPT “Brand Twin” that writes LinkedIn posts, Instagram captions, and other copy in your specific brand voice.

beginner 3 steps

Introduction

Learn how to create a custom GPT “Brand Twin” that writes LinkedIn posts, Instagram captions, and other copy in your specific brand voice. You will produce a reusable GPT trained on your brand kit, writing samples, and a forbidden-word list, helping you spend less time editing generic AI output.

Use a brand with a unique, recognizable voice as a reference when building your own. The source example used Liquid Death and an old version of their brand kit as a template.

Step-by-step 3 steps

Instructions

  1. Step 1 of 3

    Analyze your brand voice

    Open a new ChatGPT thread in the phone or desktop app. Upload 3–5 examples of your best writing, plus your brand kit if you have one.

    Tell ChatGPT:

    Prompt 
    Analyze these uploads to extract my brand's “DNA” for a Custom GPT System Prompt. Identify the specific voice posture, sentence cadence, and vocabulary preferences, while creating a strict “Forbidden List” of corporate cliches and AI-isms to avoid. Specifically, define syntactic constraints—such as banning em-dashes or “not just A, but also B” structures—to ensure the output never reverts to generic AI slop.
  2. Step 2 of 3

    Create your custom GPT

    • Navigate to https://chatgpt.com/gpts in your web browser and click “Create” in the top right.
    • Name your GPT and paste in the system instructions you generated in Step 1.
    • Upload your writing samples and brand kit.
    • Keep everything else as the default settings.
    liquid_death_brand_twin
  3. Step 3 of 3

    Share and pin your Brand Twin

    Click Share > GPT Store. Then open the ChatGPT desktop app and click GPTs > Explore GPTs > Search Public GPTs.

    Find your GPT and click “Start Chat.” Click the name at the top, then click “Pin GPT.”

    pin_gpt

You're done

That's the whole workflow

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Overview Back to the steps

Background and context

Who This Is Useful For

  • Marketing managers who are tired of rewriting most AI-generated copy
  • Content leads who want to scale a specific brand voice across a team
  • Entrepreneurs who do not know where to start with their brand voice

What You Will Build

A custom GPT “Brand Twin” trained on your specific brand kit, best writing samples, and a forbidden list of corporate clichés and AI-isms.

  • Custom GPT system instructions based on your brand DNA
  • Uploaded writing samples and optional brand kit inside the GPT
  • A pinned GPT that your team can reuse for brand-aligned copy

What You Need

  • ChatGPT Plus ($20/month)
  • 3–5 samples of your best writing, such as PDFs, markdown files, or text files
  • Optional: a brand kit slide deck

Going Further

  • Test your new GPT by using the same prompt in your Brand Twin and in a temporary ChatGPT thread, then use the comparison to refine your system instructions.
  • If a teammate writes copy for your brand, have them add the GPT and ask it to grade how well their copy fits your brand voice on a 1–10 scale.